Telephones and Telephone Exchanges.

[John]

When I started at Clifton around 1964, it had an automatic telephone exchange for the surface phones and a manual exchange for U/G.
All underground phones were the Ericson magneto crank type with the dual headpieces all in a cast iron casting with hinged lid. Used to love them when they developed a fault, those headpieces used to give a good jolt when someone on the same line cranked their magneto....Surface manual exchange was manned 24 hours.

Then it was dial auto phones at Cotgrave, dial auto phones at BG's Marblaegis mine, all auto phones at Boulby, with a central control room with a DAC terminal for the Mine Clerk.
Auto phones at Renison Bell Tin mine, auto phones at Wongawilli Colliery, oddly the U/G phone exchange was located underground!! I still find that a peculiarity...The colliery was a damp to wet pit, plus the safety aspect of the whole underground telephone system being installed in a hazardous location, making it vulnerable to a roof fall, fire, explosion, and cutting off all U/G communication to the surface.
Angus Place was fully auto dial phones, auto exchange was in the electrical workshop.

[bulwellbrian]

The NCB/BCC telephone systems evolved like telephones everywhere.

When I started at Cinderhill Laboratory there were two systems, a dial phone which could reach all similar dial phones at Babbington colliery, and a phone without a dial for all other calls when you asked the colliery operator for the number required.

When I retired from Hobart House there was one phone on my desk from which you could dial throughout the NCB/BCC including underground, you also dialed 9 for an outside line for BT calls. My number was 34993, all Hobart House numbers were 34xxx. We used to get phone calls that were obviously from underground, they liked to make nuisance calls to HQ.